Convert camelCase and snake_case to Word Case

toWordCase.js

const noVowelsToUpper = key => key.match(/[aeiouy]/) ? key : key.toUpperCase()

const lowerCaseTwoLetter = w => {
  const words = [ 'of', 'to', 'in', 'it', 'is', 'as', 'at', 'by', 'or', 'on', 'if', 'an' ]
  if (w.length === 2 && words.indexOf(w.toLowerCase()) >= 0) return w.toLowerCase()
  return w
}
const upperCaseTwoLetter = w => {
  const words = [ 'CA', 'ID' ]
  if (w.length === 2 && words.indexOf(w.toUpperCase()) >= 0) return w.toUpperCase()
  return w
}

const upperCaseReplace = w => {
  const patterns = [
    [/guid$/, ' GUID'],
    [/uuid$/, ' UUID'],
    [/id$/, ' ID'],
  ]
  patterns.forEach(p => w=w.replace(...p))
  return w
}

const lowerCaseReplace = w => {
  const patterns = []
  patterns.forEach(p => w=w.replace(...p))
  return w
}

const camelToSnake = str => str.replace(/[A-Z]/g, letter => `_${letter.toLowerCase()}`)

const initCase = w => w[0].toUpperCase() + w.slice(1)

const toWordCase = w => {
  if (!w) return w
  return camelToSnake(w).toLowerCase().split(/[ _]/).filter(w=>!!w)
    .map(noVowelsToUpper)
    .map(upperCaseTwoLetter)
    .map(upperCaseReplace)
    .map(initCase)
    .map(lowerCaseTwoLetter)
    .map(lowerCaseReplace)
    .join(' ')
}

export default toWordCase